Referring to FIG. 11, there is shown a conventional structure that secures an intermediate portion of an electrical wire of a wiring harness to a body such as a connector housing to ensure that the stress that is caused when an electrical wire is pulled be not transferred to a caulking part or other relevant portions (see FIG. 11). The structure shown in FIG. 11 includes an electrical wire 101, a housing 102, a CS-ring 103, a stopper ring 104, and a telescopic tube 105.
Sheathed electrical wires 101a are covered by an outer insulating cover 101b to form the electrical wire 101, and a terminal fitting is attached to one end of the sheathed electrical wire for example by exposing its core wire to an outside. The housing 102 is formed by insulating synthetic resin approximately in a shape of a cylinder. The hole that passes through the housing 102 includes a large-diameter portion 102a and a small-diameter portion 102b that has a diameter smaller than that of the large-diameter portion 102a, to which the small-diameter portion 102b continues, with a step portion 102c defined at the boundary of the large-diameter portion 102a and the small-diameter portion 102b. 
The CS-ring 103 is formed in a shape of a ring, and an inner diameter of the ring is larger than an outer diameter of the outer insulating cover 101b. Also, the CS-ring 103 has a plurality of protruding pieces 103a protruding radially inward of the ring. A diameter of an imaginary circle obtained by connecting tips of the protruding pieces 103a (i.e., “totsu-naikei”, which means a convex inner diameter) is smaller than the outer diameter of the outer insulating cover 101b. The stopper ring 104 is formed in a shape of a ring, and an inner diameter of the ring is substantially identical with the outer diameter of the CS-ring 103 and an outer diameter of the ring is substantially identical with the large-diameter portion 102a of the housing 102. The telescopic tube 105 is attached to the outer surface of the outer insulating cover 101b. 
The CS-ring 103 is attached to an inner diameter portion of the stopper ring 104 and is attached to the electrical wire 101. Thereafter, it is mounted inside of the housing 102 such that one side of the stopper ring 104 is in contact with the step portion 102c. 
Also, a known strain relief for use in securing an electrical conduction cable to an electrical connector is disclosed in Patent Literature 1.